1. Field of the Invention
This invention relates to electronic musical tone synthesis and in particular is concerned with the simultaneous control of independent tone generators from a single keyboard.
2. Description of the Prior Art
Some of the current electronic muscial instruments are implemented with a conventional upper, or solo, keyboard as well as with a monophonic synthesizer which is keyed from an independent and separate synthesizer keyboard. In some of these instruments a means is provided so that the monophonic synthesizer can be played from the upper keyboard in combination with the tones that are also assigned to the upper keyboard. When this coupling mode is used each note keyed on the upper keyboard will cause a sound to be generated which corresponds to the tone controls selected for the upper keyboard. In addition, the highest frequency upper keyboard note will also act to produce the tone selected for the monophonic synthesizer keyboard. An important alternative arrangement is to have the highest frequency note keyed on the upper keyboard sound the monophonic synthesizer but not sound the tones selected for the upper keyboard.
A system is disclosed in U.S. Pat. No. 4,186,637 whereby one of a set of tone generators is designated as a solo high tone generator and is always utilized to produce the highest note that is sounded. The highest keyed note on the keyboard is simultaneously assigned to two tone generators operated at the same fundamental frequency. One of the generators is a member of the set of tone generators associated with the keyboard and the second is the dedicated solo high tone generator.
A system is disclosed in U.S. Pat. No. 4,342,248 for a keyboard operated electronic musical instrument in which in response to an actuated keyswitch a tone generator is assigned with a musical waveshape selected from a library of waveshapes which are ordered in a predetermined arrangement. The assignment of waveshapes is made in a priority order according to the musical frequencies associated with the actuated keyswitches so that a chorus effect is obtained in which each note of a group of simultaneous notes has its own tone color. The assignment of waveshapes is made in an adaptive manner so that the melody line retains its own distinctive sound even when the number of notes played simultaneously on a keyboard changes.